1. Field of the Invention
The present invention relates to a macromolecular adsorbent for adsorbing heavy metal ions. More particularly, it relates to macromolecular adsorbent suitable for recovering heavy metal ions from a dilute solution.
2. Description of Prior Arts
It has been proposed to use inorganic adsorbents such as titanic acid, aluminum hydroxide, iron hydroxide, lead sulfide, and basic zinc carbonate, especially titanic acid having high adsorbing function supported on activated carbon, as an adsorbent for collecting trace components such as uranium component in sea water, in Japanese Patent Publication No. 648/1974.
These inorganic adsorbents have disadvantages that a molding is not easy and brittle in comparison with an organic adsorbent and a recovery efficiency is remarkably decreased by repeating adsorption-desorption.
On the other hand, it has been also proposed to use organic adsorbents such as arsonic acid type resins (such as British Pat. No. 948,962), hydroxyphenyl compound-formaldehyde condensates having phosphono group bonded to the aromatic ring (Japanese Unexamined Patent Publication No. 114510/1977). These organic adsorbents have disadvantages that toxic arsenic compound is used as a starting material or adsorbing functions and durabilities are not satisfactory for practical applications.